Ezekiel, like any of his contemporaries, would have known that Nebuchadnezzar had no navy with which to siege an island. This is relevant because, then no contemporary prophet would choose to prophesy that he would siege the island.
Each of the attacks specifically attributed to Nebuchadnezzar are blatantly land-specific; they are applicable only to the coastal district of Tyre. For example,…
• …“siege walls”1
• …“battering rams”
• …“roof of shields”2
• …“multitude of his horses, the dust raised by them will cover you.”
• …“strong pillars”3
[Keep in mind that even if Nebuchadnezzar had a navy (which he did not), the walls of insular Tyre hugged the edge of the island in a way that would not even allow battering rams, siege walls, or a roof of shields. That is, unless Ezekiel somehow anticipated the building of a massive mole out to the island, one that in Alexander's day was considered perhaps the greatest war-engineering feat in history. Ezekiel would not have expected this as a way to reach the island.]
In Ezekiel's description of Nebuchadnezzar's attacks, there is a blatant absence of naval representation (no “boats”, “ships”, or the like). This is relevant because the description is rather long, varied, and vivid (see above); had this been a naval siege, the graphical description would have been themed completely differently.
Isn't it the case that only the Island called Tyre was fortified? • …Ashurbanipal didn't mention walls on Ushu (The structures along Tyre's coast) This would be relevant because Nebuchadnezzar's siege on Tyre was prophesied to be an attack on a fortified city.1
Ezek 26:9 --“The blow of his battering rams he will direct against your walls, and with his axes he will break down your towers.” (c.f v 4. 8, 12)
In Ezekiel's prophecy on Tyre, the “many nations” which are to entirely destroy Tyre are in fact just Nebuchadnezzar's multi-national army. This is relevant because Tyre was largely identified with her prestigous island, such that a destruction of Tyre would require a destruction of the island.
Look at the prophecy. The attacks assigned to Nebuchadnezzar (v8b-11) are not just addressed to “your daughters” (the mainland suburbs); in v.8 we see they were also addressed to “you.”1 This is relevant be cause the “you” there is a reference to the island in particular. Therefore, both the coastal suburbs and the island are supposed to come under Nebuchadnezzar's siege.
By way of response however, the word “you” in Ezekiel's prophecy absolutely does not “refer to the island in particular”; it refers to Tyre itself as a city and the extensive line of suburbs on the coast are universally acknowledged to be a district of it. Consequently, Ezekiel simply designates “your daughters” (i.e. your coastal suburbs) as the specific point at which “you” (Tyre) will be attacked by Nebuchadnezzar.
In Ezekiel 29, the prophet admits that his prophecy failed. After all,
• …Tyre was to be spoil for the nations
• …God's reward to Nebuchadnezzar is recompense
This is relevant because it implies that Nebuchadnezzar was supposed to have been successful in his attack on Tyre, and yet, the only sense in which Nebuchadnezzar's attack was not successful is that he was not able to attack the island.